The invention relates to a method designed to check the aseptic nature of washing contained in a washing machine, prior to the opening of at least one door of this machine that opens into a clean room.
The invention is particularly applicable to washing machines used in industrial or semi-industrial laundries which process washing coming from hospital premises. Such machines are generally fitted with at least one door opening into a contaminated room which is used to load the dirty washing into the machine and at least one door opening into a clean room and used to unload the washing when the washing is finished. In a more general way, the invention may nevertheless be applied to other types of washing machines and notably to machines fitted with a single door, when such machines are used in such a way that the washing is unloaded into a clean room.
In industrial laundries intended for the treatment of washing from hospital premises, the washing is generally washed in washing machines integrated into a partition separating a contaminated room from a clean room. The machine then comprises at least one door opening into the contaminated room and used for loading the dirty washing and at least one door opening into the clean room and used to unload the washed laundry.
In a laundry of this type, the opening of the door or doors of the machine opening into the clean room is generally commanded by an opening order supplied by a controller which operates the machine when the washing-rinsing-spin drying cycle is finished.
In most cases, the washing which is taken out of the machine into the clean room effectively provides the desired conditions of hygiene and asepsis due to the carrying out of the washing-rinsing-spin drying cycle commanded by the controller.
However, it may happen that the cycle effectively carried out by the machine is defective and does not enable one to guarantee the total destruction of pathogenic bacteria present in the washing. For example, the troughs containing detergent products may be empty or the heating system of the machine may be broken down. The washing-rinsing-spin drying cycle is then commanded normally by the controller and an order for the opening of the door or doors opening into the clean room is given at the end of the cycle.
In existing washing machines, the door or doors opening into the clean room can therefore be opened when the required conditions of asepsis of the washing have not been achieved. Considering the dangers presented by certain pathogenic bacteria which are to be found in washing coming from hospital premises, it is highly desirable to have washing machines available in which this risk is totally eliminated.
The precise subject of the invention is a method that makes possible the checking of the aseptic nature of the washing before opening the door or the doors of washing machine opening into a clean room, so that his opening is not authorized when it is not certain hat the conditions of asepsis of the washing have been achieved.
Conforming to the invention, this result is obtained by means of a method of checking the aseptic nature of the washing prior to the opening of at least one door of a washing machine, characterized in that it comprises, the following successive steps in this order:
checking the arrival of a minimum quantity of water in the tank of the machine;
checking the presence of detergent products in said tank;
verifying that a minimum temperature is achieved by the water contained in said tank;
emission of a signal authorizing the opening of said door, a predetermined interval of time after obtaining said minimum temperature in said tank.
By enabling one to ensure that the washing water and then the detergent products have been properly introduced into the tank of the machine and by afterwards checking that the water bath thereby obtained has been properly heated to the desired temperature for a minimum time interval, the method according to the invention guarantees total destruction of the pathogenic bacteria initially present in the washing. Since authorization to open the door is only given when these various checks have been carried out, it then becomes possible to guarantee perfect hygiene of the washing when the door of the washing machine is opened.
According to an improvement in the invention, checking the arrival of said minimum quantity of water is followed by a check on the rotation of the drum of the machine. It is then certain that the mixing of the water bath made up of the mixture of water and detergent products has been ensured.
According to one preferred embodiment of the invention, the washing machine is integrated into a sealed partition separating a contaminated room from a clean room and it has at least one door opening into each of these rooms. Each door opening into the clean room is then locked, in the closed state, until the emission of the signal authorizing opening.
So as to check the arrival of the minimum quantity of water in the tank of the machine, the flow rate, volume or mass of the water admitted to the tank may be measured or the height of the water in the tank may be measured.
In addition, the check on the presence of the detergent products can be provided either by measuring the pH of the water bath contained in the tank, or by measuring the total hardness of this water bath or by checking the arrival of the detergent products in the tank.
When the check of the presence of the detergent products is provided by a pH measurement, one may advantageously verify that the pH of the bath is at least equal to about 9.
In the preferred embodiment of the invention, it is verified that the water bath achieves a minimum temperature of at least about 60xc2x0 C. In addition, the signal for opening the door is emitted advantageously 20 minutes after this minimum temperature has been reached.